It's not at the storage edge. It's actually at the server-to-network infrastructure connection point. It's all of the cables, NICs, HBAs and switches required to gain connectivity to the plethora of servers in the data center.
"You'll recognize this common server deployment strategy in your data center : LAN and SAN switch devices used to connect to host servers are smaller pizza box access/edge switches that are physically located at the "top of the rack" of servers to provide connectivity. These top-of-rack switches typically have a series of uplinks to larger chassis-based or director-class aggregation or core switches that provide communication across all of the rack of servers in one or more data centers